Surface reactivity of non-hydrolytic silicophosphate xerogels: a simple method to create Bronsted or Lewis acid sites on porous supports

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Publikace nespadá pod Ekonomicko-správní fakultu, ale pod Středoevropský technologický institut. Oficiální stránka publikace je na webu muni.cz.
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STÝSKALÍK Aleš ŠKODA David MORAVEC Zdeněk BARNES Craig E. PINKAS Jiří

Rok publikování 2016
Druh Článek v odborném periodiku
Časopis / Zdroj New Journal of Chemistry
Fakulta / Pracoviště MU

Středoevropský technologický institut

Citace
www http://pubs.rsc.org/en/Content/ArticleLanding/2016/NJ/C5NJ02928G#!divAbstract
Doi http://dx.doi.org/10.1039/c5nj02928g
Obor Anorganická chemie
Klíčová slova Non-hydrolytic; sol-gel; silicon acetate; silicophosphate; xerogel; heterogeneous; catalysis; Lewis acid; Bronsted acid
Popis Non-hydrolytic sol-gel reactions of silicon acetates with trimethylsilyl (TMS) esters of phosphoric and phosphonic acids produce cross-linked matrices containing homogeneous dispersions of silicate and phosphoryl groups connected together by networks of Si-O-P(QO) linkages. The condensation degrees reach 80 to 90%. Residual organic groups (10 to 20%) were reacted with a variety of compounds (H2O, Me3SiOSiMe3, POCl3, SiCl4, AlMe3, Al(NMe2)(3), and AlCl3) in order to enrich the surface of these porous matrices with Bronsted (RP-OH) and Lewis (tetracoordinated Al) acid functional groups. The differences in the reactivity of RSi-OAc and RP-OSiMe3 groups were utilized for the selective modification at the silicon and phosphorus atoms. The reaction procedures were optimized and significantly porous silicophosphate materials with a high content of either hydroxyl groups or four-coordinated aluminium species were obtained. The activity and selectivity of prepared samples as catalysts for the dimerization of a-methylstyrene were tested. Excellent activities and moderate to very high selectivities were achieved suggesting the potential use of silicophosphate xerogels in heterogeneous catalysis.
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